1. Field of the Invention:
The present invention relates to a method of forming a seam in a body outer panel of a vehicle like an automobile.
2. Description of the Prior Art:
The body outer panel of a vehicle like an automobile is usually constructed of a plurality of plate elements which have been preformed by a press, said elements being joined with each other thereby forming a seam at the joining portion. For example, as shown in FIG. 1, side wall portions of an automobile provided at opposite sides of a rear window 1 include seams 4 formed between a roof panel 2 and quarter panels 3. These seams should preferably be formed so as not to be noticed by the outerside viewer. For this purpose, the seam 4 is conventionally formed by the procedures as shown in FIG. 2. Explaining in detail, as shown in FIG. 2(a), the roof panel 2 and the quarter panel 3 are bent toward the rear side of the panels by a relatively large amount at the portions to form the seam 4, thereby providing a cavity 6 retracted from a favorable smooth contour surface 5 which the body outer panel should present. With the bent portions being laid one over the other as shown in the figure, the roof panel 2 and the quarter panel 3 are welded together by spot welding to provide an assembled panel structure having co-welded portions 7. Thereafter, as shown in FIG. 2(b), solder is mounded as shown by 8 to fill the cavity 6. As seen in the figure, the solder mounding 8 is formed to project beyond the contour surface 5. Then, as shown in FIG. 2(c), the portion of the solder mound projecting from the contour surface 5 is removed by grinding or the like so as to form the contour surface 5 which smoothly connects the roof panel 2 and the quarter panel 3.
The conventional method of mounding a lump of solder presents a problem regarding an occupational disease in that the worker's health can be injured by the atmosphere produced by soldering. With regard to the quality of this product, the conventional method is not advantageous because the quality rapidly deteriorates by generation of pinholes or blisters, making it difficult to obtain a good finish of the painted surface. Furthermore, the conventional method has an economical disadvantage because it requires a large amount of manpower and materials.
Other conventional methods such as helium arc welding, solder welding, etc. are known. However, these welding methods have the drawback that when they are applied to a thin plate like a body outer panel of an automobile, a distortion is caused at the seam, requiring a large amount of work for correcting same.
As an art similar to the abovementioned solder mounding, plastics have been used in place of solder. However, when plastics are used, electrostatic painting cannot be employed in the painting process and, furthermore, this method is still bound with pinhole and/or blister problems.